The invention relates to a device and method for compensating a machine tool's position-dependent compliance, to a machine tool that includes a device of said type, and to a computer program for implementing a method of the cited kind.
A compromise between as short as possible machining time and as high as possible finishing accuracy often has to be accepted when workpieces are machined, in particular cut, by means of a machine tool. The production process is basically designed such that a minimally required finishing accuracy will be maintained everywhere on the workpiece being machined and at all times during machining. Given these boundary conditions, maximum possible feed rates and cutting parameters must be targeted for the machine tool in order to ensure as economical as possible production.
Said maximum possible parameters depend substantially on the machine tool used. For example, parameters such as feed rates, cutting depths, tools employed etc. and the process forces resulting therefrom will impact substantially on the achieved contour fidelity depending on the machine tool's rigidity.
The machine's rigidity is as a rule dependent on the current positioning of the machine tool's axes or, expressed another way, on the tool's current position within the machine's operating space. Rigidity or, as the case may be, its reciprocal, compliance, will hence vary during a machining operation during which what is termed the tool center point (TCP) moves within the operating space. Clearly visible contour deviations can consequently occur while a workpiece is being machined if constant parameters for feed rate, cutting depth and spindle speed are used during machining. A pre-specified contour fidelity can nonetheless be achieved by dimensioning the cited machining parameters taking account of the machine tool's greatest compliance.